A steward is an employee responsible for some duties within a larger organization. It could be a manager or in the use of the word today it could simply be a responsible employee.
Duties of a steward could involve money or financial assets or could revolve around food (in a restaurant) or customer service (on a ship) as examples. In the Bible, as one would expect, the duties of a steward are connected with ones responsibility to God.
In consideration of the Bible teaching that God created everything, God is the ultimate owner and delegates responsibilies as he sees fit. As subjects in this spiritual organization we would expect to discover our duties and responsibilies specified in the Holy Bible. These duties and responsibilities are indeed to be found in the Bible.
The basic question one needs to answer is regarding ones acceptance of the role. Do you accept that God owns you and all that over which you have a measure of control or influence? Are you committed to do your best to comply and follow the instructions you are given? Are you willing to apply mental effort to uncover your duty to God?
How are you behaving with respect to God's instructions and the resources God has put in your hands?
Twice in the Bible book of First Corintians it is stated that "you are bought with a price". Said another way, God owns you twice over. God created you, gave you life and then paid a second time when Jesus Christ died to get you back from the clutches of sin.
What SDAs Believe About Biblical Stewardship
The Parable of the Talents (Wikipedia)
Stewardship (theology) (Wikipedia)
What is Biblical Stewardship? (R.C. Sproul)
Stewarding the Kingdom (Freddy Cardoza)